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Bahan kajian pada MK Pertanian Berlanjut

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1 Bahan kajian pada MK Pertanian Berlanjut
HIDROLOGI LANSEKAP DAN RAINWATER HARVESTING Diabstraksikan oleh: smno.jursntnh.fpub. okt 2012

2 HIDROLOGI…. “HIDROLOGI”
…. Kajian ilmiah tentang sifat-sifat, distribusi dan efek-efek air di permukaan bumi, di dalam tubuh tanah, di dalam batuan bawah tanah, serta air di atmosfir. ….. Siklus Hidrologi Diunduh dari Sumber: 17/10/2012

3 PENTINGNYA VEGETASI POHON DALAM SIKLUS HIDROLOGI….
Aliran air dalam siklus hidrologi: Evaporasi air dari permukaan; Transpirasi oleh tumbuhan; Transport air di atmosfir; Presipitasi (Hujan); Limpasan permukaan (runoff) dan aliran bawah permukaan. Diunduh dari Sumber: 17/10/2012

4 NERACA AIR DAN NERACA ENERGI …. POHON….
Precipitation (P) is any and all forms of water that fall from clouds and reach the ground. Runoff (R) is the water from precipitation that is not absorbed into the soil, but flows and reaches a stream or another body of water. Evapotranspiration (E) is water evaporating from wet surfaces and the soil plus the water release of plants. Diunduh dari Sumber: 17/10/2012

5 Air hujan yang jatuh dari langit :
PENTINGNYA HUTAN DALAM SIKLUS HIDROLOGI…. Air hujan yang jatuh dari langit : Menguap kembali ke atmosfir, mengalir di permukaan lahan (runoff), meresap ke dalam tanah (infiltration). Proses-proses di atas dikendalikan oleh intensitas hujan, karakteristik tanah dan lahan, kemiringan lahan dan vegetasi. Diunduh dari Sumber: 17/10/2012

6 DAERAH ALIRAN SUNGAI (DAS) …. WATERSHED
DAS meliputi semua lahan yang menyalurkan air hujan memasuki suatu sistem sungai tertentu. DAS menangkap dan menyimpan air hujan, melepaskan air tersebut secara bertahap memasuki alur sungai. Perubahan dalam suatu DAS, secara alamiah atau buatan manusia, akan mempengaruhi kualitas air, kecepatan runoff, nilai habitat dan erosi , yang pada akhirnya akan berdampak pada keseluruhan DAS. Diunduh dari Sumber: 17/10/2012

7 Annual water balance for the Walnut Gulch Experimental Watershed.
…NERACA AIR DI BENTANG LAHAN. Annual water balance for the Walnut Gulch Experimental Watershed.      The Walnut Gulch Experimental Watershed is located primarily in a high foothill alluvial fan portion of the San Pedro River watershed.  Cenozoic alluvium is very deep and is composed of coarse-grained fragmentary material, the origin of which is readily traceable to present-day mountain flanks on the watershed.  Diunduh dari Sumber: 17/10/2012

8 RAIN-WATER HARVESTING
Panen air hujan merupakan suatu metode memanfaatkan air hujan untuk keperluan domestik dan pertanian, cara ini telah banyak diaplikasikan di berbagai penjuru dunia. DELAPAN PRINSIP KEBERHASILAN PANEN AIR HUJAN: Mulai dari observasi lapangan dengan hati-hati dan kontinyu. Mulai dari titik tertinggi drai bentang-lahan atau petakan lahan dan bekerja menuruni kemiringan lahan. Mulai dari kerja kecil dan sederhana. Memperlambat, menyalurkan dan menginfiltrasikan air hujan. Merencanakan saluran pelimpas dan memanfaatkan air limpasan sebagai sumberdaya. Memaksimumkan komponen organik /vegetatif dari tutupan lahan. Memaksimumkan fungsi dan relasi-relasi yang baik dnegan jalan “stacking functions.” Memonitor hasil kerja dan memperbaikinya terus menerus. Diunduh dari Sumber: smno fpun… 17/10/2012

9 Diunduh dari Sumber: ….. 17/10/2012
Rain Garden. “A rain garden” adalah sekungan di permukaan lahan yang ditanami (tumbuhan) yang memungkinkan air hujan yang mengalir dari lahan di sekitarnya ditampung dan diresapkan ke dalam tanah. Hal ini dapat mengurangi runoff air hujan dan memungkinkan air hujan meresap ke dalam tanah , sehingga dapat mengurangi ancaman erosi, pencemaran air, banjir dan kurangnya pasokan air ke dalam groundwater. “Rain garden’ ini dapat mengurangi pencemaran perairan dan sungai hingga sebesar 30%. Diunduh dari Sumber: ….. 17/10/2012

10 Diunduh dari Sumber: www.gardenforglobalwarming.co.uk/2008.html
CONTOH RAIN GARDEN…. Diunduh dari Sumber: ….. 17/10/2012

11 …EMBUNG PERTANIAN. Embung atau tandon air merupakan waduk berukuran mikro di lahan pertanian ( small farm reservoir) yang dibangun untuk menampung kelebihan air hujan di musim hujan. Air yang ditampung tersebut selanjutnya digunakan sebagai sumber irigasi suplementer untuk budidaya komoditas pertanian bernilai ekonomi tinggi di musim kemarau atau di saat curah hujan makin jarang. Embung merupakan salah satu teknik pemanenan air HUJAN yang sangat sesuai di segala jenis agroekosistem. Pembuatan embung untuk pertanian bertujuan antara lain untuk : Menampung air hujan dan aliran permukaan ( run off) pada wilayah sekitarnya serta sumber air lainnya yang memungkinkan seperti mata air, parit, sungai-sungai kecil dan sebagainya. Menyediakan sumber air sebagai suplesi irigasi di musim kemarau untuk tanaman palawija, hortikultura semusim, tanaman perkebunan semusim dan peternakan. Diunduh dari Sumber: ….. 17/10/2012

12 . PERSYARATAN LOKASI EMBUNG….
Daerah pertanian lahan kering/perkebunan/ peternakan yang memerlukan pasokan air dari embung sebagai suplesi air irigasi. Air tanahnya sangat dalam. Bukan lahan berpasir. Terdapat sumber air yang dapat ditampung baik berupa air hujan, aliran permukaan dan mata air atau parit atau sungai kecil. Wilayah sebelah atasnya mempunyai daerah tangkapan air atau wilayah yang mempunyai sumber air untuk dimasukkan ke embung, seperti mata air, sungai kecil atau parit dan lain sebagainya. Konstruksi pembangunan embung dapat dilakukan oleh kelompok tani secara padat karya dan bertahap. Diunduh dari Sumber: bebasbanjir2025.wordpress.com/.../embung/ ….. 17/10/2012

13 INFILTRASI Some of the precipitation that falls on land seeps into the ground where it is stored in aquifers and is transported to streams and lakes by subsurface flow. The amount of infiltration is influenced by the permeability and moisture content of the soil, the presence of vegetation and the volume and intensity of precipitation. The amount of water in an aquifer is indicated by the height of the water table (the upper boundary of aquifer). Diunduh dari Sumber: 17/10/2012

14 INFILTRASI Infiltration is the downward movement of water from the land surface into the soil profile. Infiltration. The downward entry of water into the immediate surface of soil or other materials. Infiltration capacity. The maximum rate at which water can infiltrate into a soil under a given set of conditions. Infiltration rate. The rate at which water penetrates the surface of the soil, expressed in cm/hr, mm/hr, or inches/hr. The rate of infiltration is limited by the capacity of the soil and the rate at which water is applied to the surface. This is a volume flux of water flowing into the profile per unit of soil surface area (expressed as velocity). Percolation. Vertical and lateral movement of water through the soil by gravity. Diunduh dari Sumber: ….. 17/10/2012

15 INFILTRASI Figure : Zones of the infiltration process for the water content profile under ponded conditions The distribution of water during the infiltration process under ponded conditions is illustrated in Figure. In this idealized profile for soil-water distribution for a homogeneous soil, five zones are illustrated for the infiltration process. Transmission zone. This zone is characterized by a small change in water content with depth. In general, the transmission zone is a lengthening unsaturated zone with uniform water content. Gravity forces primarily drive hydraulic gradient in this zone. Diunduh dari Sumber: ….. 17/10/2012

16 INFILTRASI Soil-water infiltration is controlled by the rate and duration of water application, soil physical properties, slope, vegetation, and surface roughness. Generally, soil-water infiltration has a high rate in the beginning, decreases rapidly, and then slowly decreases until it approaches a constant rate. As shown in Figure , the infiltration rate will eventually become steady and approach the value of the saturated hydraulic conductivity. Source: Hillel, 1982 whenever water is ponded over the soil surface, the rate of infiltration exceeds the soil infiltration capacity. Diunduh dari Sumber: ….. 17/10/2012

17 SISTEM INFILTRASI Surface infiltration can be achieved through the use of grass buffer strips, vegetated swales, and porous pavement systems. Infiltration systems such as infiltration trenches, infiltration basins, and bioretention areas (including rain gardens) are designed specifically to capture a defined volume of storm runoff and transfer it directly to the soil profile. Several integrated practices, such as soil quality restoration and native landscaping, can be used in conjunction with these practices to improve the infiltration capacity of compacted urban soils. An infiltration BMP is designed to capture a volume of stormwater runoff, retain it, and infiltrate all or part of that volume into the ground. Diunduh dari Sumber: ….. 17/10/2012

18 Infiltration hydraulics and process….
. A fundamental principle for describing the flow of water in a homogeneous, porous media is given by Darcy’s Law (Chow, Maidment, and Mays, 1988; McCuen, 1989): Q = KA h/L where: Q = flow (cfsec); K = saturated hydraulic conductivity; characteristic of a specific porous medium when effectively saturated with water (fps); A = cross-sectional area through the porous medium perpendicular to the flow (ft2); h/L = hydraulic gradient, the difference in hydraulic head,h, per unit distance in the direction of flow, L ft/ft The velocity of flow through the porous medium can be determined from Equation 1 by substituting the continuity equation Q = qA to obtain: q = K (h/L) where: q = velocity of water through a unit cross section of the porous medium (fps)  The velocity of water through the pores of the medium is described by: V = q/s  where: V = fluid velocity (in/hr); s = water content of the medium (in3/in3) equal to the medium’s porosity less the volume of trapped air in the pore spaces. Diunduh dari Sumber: ….. 17/10/2012

19 Soils and infiltration….
Factors that control infiltration rate and capacity: Vegetative cover, root development, and organic content Moisture content Soil structure and texture Porosity and permeability Soil bulk density and compaction Slope, landscape position, and topography Hydrologic soil group (HSG). The HSG refers to the soil characteristics that tend to decrease or increase the amount of runoff produced from a precipitation event. The HSG is used in the determination of the runoff curve number (CN) developed by the Natural Resource Conservation Service (NRCS). Group A. Sand, loamy sand, or sandy loam soil types. Low runoff potential and high infiltration rates, even when thoroughly wetted. Includes deep and well- to excessively-drained sands and gravels. High rate of water transmission (hydraulic conductivity). Group B. Silt loam or loam. Moderate infiltration rate when thoroughly wetted. Includes moderately deep to deep, moderately well- to well-drained soils. Moderately fine to moderately coarse textures. Diunduh dari Sumber: ….. 17/10/2012

20 Soils and infiltration….
Group C. Sandy clay loam. Low infiltration rates when thoroughly wetted. Consists primarily of soils with a layer that impedes downward movement of water. Moderately fine to fine structure. Perched water table at inches; root-limiting at inches. Soil texture. The hydrologic design methods presented are based on the use of two hydrologic soil properties; the effective water capacity (Cw) and the minimum infiltration rate (f) of the specific soil textural groups. Effective water capacity. The fraction of the void spaces available for water storage (in/in). Minimum infiltration rate. The final rate that water passes through the soil profile during saturated conditions (in/hr). Group D. Clay loam, silty clay loam, sandy clay, silty clay, and clay. Very low infiltration rates when thoroughly wetted. Consists chiefly of clay soils with high swelling potential, soils with a permanent high water table, soils with a claypan or clay layer at or near the surface, and shouldow soils over nearly impervious material. Diunduh dari Sumber: ….. 17/10/2012

21 Hydrologic soil properties classified by soil texture
Soil texture class Hydrologic soil group Effective water capacity (Cw) (in/in) Minimum infiltration rate (f) (in/hr) Effective porosity, θe (in3/in3) Sand A 0.35 8.27 ( ) Loamy sand 0.31 2.41 ( ) loam B 0.25 1.02 ( ) Loam 0.19 0.52 ** ( ) Silt loam C 0.17 0.27 ( ) Sandy clay loam 0.14 ( ) Clay loam D 0.09 ( ) Silty clay loam 0.11 0.06 ( ) clay 0.05 ( ) Silty clay 0.04 ( ) Clay 0.08 0.02 ( ) Note: Minimum rate: soils with lower rates should not be considered for infiltration BMPs Diunduh dari Sumber: ….. 17/10/2012

22 Screening criteria for infiltration practices ….
Evaluation of the viability of a particular site includes: Determine soil type from mapping and soil survey to review other parameters such as the amount of silt and clay, presence of a restrictive layer or seasonal high water table, and estimated permeability. The soil should not have more than 30 percent clay or more than 40 percent clay and silt combined. Eliminate sites that are clearly unsuitable for infiltration. If the surface and underlying soils are Group D or the saturated infiltration rate is less than 0.52 in/hr, the site should not be used for infiltration. Groundwater separation should be at least 4 feet from the basin invert to the measured groundwater elevation. Seasonal high groundwater should be a minimum of 4 feet below the infiltration surface. Bedrock or impervious soils should be a minimum of 4 feet from the infiltrating surface (i.e. bottom of trench). Location should be the following distances away from structures: 1). Buildings, slopes, and highway pavement: greater than 25 feet 2). Wells and bridge structures: greater than 100 feet. Infiltration practices should not be placed in locations that cause water problems to downgrade properties. Infiltration facilities should be set back 25 feet (10 feet for dry wells) down-gradient from structures. Diunduh dari Sumber: ….. 17/10/2012

23 Point system for the evaluation of potential infiltration sites
1 Ratio between tributary-connected impervious area (AIMP) and the infiltration area (AINF): AINF > 2 AIMP 20 points AIMP ≤ AINF ≤ 2 AIMP 10 points 0.5 AIMP ≤ AINF ≤ AIMP 5 points Urban catchments with pervious surfaces smaller than 0.5 AIMP should not be used for infiltration. 2 Nature of surface soil layer: Coarse soils with low ratio of organic material 7 points Normal humus soil Fine grained soils with high ratio of organic material 0 points 3 Underlying soils: If the underlying soils are coarser than surface soils, assign the same number of points as for the surface layer under criterion #2. If the underlying soils are finer-grained than the surface soils, use the following points: Ø      Gravel, sand, or glacial till with gravel or sand Ø      Silty sand or loam Ø      Fine silt or clay Diunduh dari Sumber: ….. 17/10/2012

24 Point system for the evaluation of potential infiltration sites
4 Slope (S) of the infiltration surface: ·         S < 7% 5 points ·         7% ≤ S ≤ 20% 3 points ·         S > 20% 0 points 5 Vegetation cover: ·         Healthy, natural vegetation cover ·         Lawn – well established ·         Lawn – new ·         No vegetation – bare ground -5 points 6 Degree of traffic on infiltration surface: ·         Little foot traffic ·         Average foot traffic ·         High foot traffic (i.e. playing/sports fields) Source: Adapted from Urbonas and Stahre, 1993 Diunduh dari Sumber: ….. 17/10/2012

25 … Types of infiltration practices.
Design methodologies are presented for three infiltration practices and two integrated (complementary) practices below: Infiltration trenches Infiltration basins Bioretention area (and rain gardens) Soil quality restoration Native landscaping. Infiltration trench and infiltration basin systems rely directly on the site soil conditions to infiltrate the design capture volume of stormwater. Infiltration trenches and basins can be used on single/multi-family residential sites of up to 10 acres and up to 5 acres for commercial sites. Diunduh dari Sumber: ….. 17/10/2012

26 Store and reuse stormwater beneficially:
Slow the Flow: Manage and Reuse Storm Water On-Site…. Store and reuse stormwater beneficially: Soil amendment and infiltration is the most cost-effective way to store rainfall for landscape use Stormwater detention vaults/cisterns, if required, may be designed to feed filtration and reuse for toilet flushing or vehicle washing, or to store late spring storms for summer landscape irrigation. Diunduh dari Sumber: 17/10/2012

27 It is measured in inches per hour or millimeters per hour.
LAJU INFILTRASI…. Infiltration is the process by which water on the ground surface enters the soil. Infiltration rate in soil science is a measure of the rate at which soil is able to absorb rainfall or irrigation. It is measured in inches per hour or millimeters per hour. The rate at which water infiltrates into a ground is called the infiltration capacity. Diunduh dari Sumber: ….. 17/10/2012

28 The rate of infiltration reaches a uniform rate after some time.
LAJU INFILTRASI…. When a soil is dry, the infiltration rate is usually high compared to when the soil is moist. For an initially dry soil subjected to rain, the infiltration capacity curve shows an exponentially decaying trend . The observed trend is due to the fact that when the soil is initially dry, the rate of infiltration is high but soon decreases, as most of the soil gets moist. The rate of infiltration reaches a uniform rate after some time. Diunduh dari Sumber: ….. 17/10/2012

29 INDEKS INFILTRASI…. The average infiltration rate is called the Infiltration Index and the two types of indices commonly used are explained in the next section. Infiltration indices The two commonly used infiltration indices are : φ – index and W – index The φ - index : the rate of infiltration above which the rainfall volume equals runoff volume. The W – index This is the average infiltration rate during the time when the rainfall intensity exceeds the infiltration rate. Thus, W may be mathematically calculated by dividing the total infiltration (expressed as a depth of water) divided by the time during which the rainfall intensity exceeds the infiltration rate. Total infiltration may be fund out as under: Total infiltration = Total precipitation – Surface runoff – Effective storm retention The W – index can be derived from the observed rainfall and runoff data. It differs from the - index in that it excludes surface storage and retention. The index does not have any real physical significance when computed for a multiple complex watershed. Like the phi-index the - index, too is usually used for large watersheds. Diunduh dari Sumber: ….. 17/10/2012

30 Keaneka-ragaman Penggunaan Lahan dan Tutupan Lahan dalam Lansekap Pertanian
Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

31 Lansekap Pertanian Lansekap Tradisional Berbagai penggunaan lahan tradisional dalam suatu lansekap mencerminkan sifat dan kondisi sumberdaya lahan (geologi, tanah, lereng, hidrologi, dsb) Lansekap Modern Intervensi teknologi (revolusi hijau) bisa memodifikasi sifat2 lahan, sehingga vegetasi tidak selalu mencerminkan sifat dan kondisi alami sumberdaya lahan Tekanan sosial dan ekonomi mengakibatkan fragmentasi dan fraksionasi lahan; ukuran individu persil semakin kecil, keaneka-ragaman dalam lansekap semakin besar Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

32 Lansekap hutan tanaman industri dataran tinggi di DAS Konto
Sumber: SMNO.hutanpinus.pujon.nop2012

33 Peta Tutupan/Penggunaan Lahan DAS Sumber Brantas (2005)
No data Sumber : Sudarto(2009) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

34 Land resources planning:
Communities Need Analysis Scenarios Feasibility Analysis Land Suitability Analysis Consumer Analysis & Participation Analysis Public Review Demand Analysis Land Resources Allocation Decision Land Capability Analysis Priority Demand Implementation, Monitoring, Evaluation, & Revision

35 Tutupan Lahan & Penggunaan Lahan di DAS Sumber Brantas
Perhatikan hal-hal berikut dalam setiap macam tutupan lahan dan penggunaan lahan yang anda lihat di DAS Brantas Hulu : Kanopi dan manajemen kanopi Pengolahan tanah (guludan, parit, dsb) Penutupan tanah (terbuka/tertutup) Pemupukan Pemberantasan Hama, Penyakit, Gulma Irigasi dan/atau Drainasi Pembuangan limbah/sampah Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

36 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi
Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

37 KEBERLANJUTAN USAHA PENANGANAN LAHAN KRITIS
Ekspor / Luar daerah HASIL Usaha Domestik Eksternal input SIAPA YG berusaha (Masyarakat) APA yang digarap ? (Lahan usaha) KEBERDAYAAN

38 Siklus Air dalam Plot PLOT
PRESIPITASI PLOT EVAPO-TRANSPIRASI INTERSEPSI LOLOS TAJUK LATERAL INFILTRASI LIMPASAN PERMUKAAN PERKOLASI DRAINASI Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

39 Siklus Air dalam Plot ? Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

40 Siklus Air dalam Plot Komponen Siklus Air (yang relevan) :
Presipitasi (Hujan) Intersepsi (oleh tajuk tanaman) Lolos Tajuk Infiltrasi Perkolasi Limpasan Permukaan Aliran Lateral (masuk dan keluar) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

41 Faktor yang mempengaruhi besaran komponen
Faktor yang berpengaruh terhadap besaran komponen siklus air di tingkat plot Komponen Siklus Air Faktor yang mempengaruhi besaran komponen Presipitasi (variabel bebas) Aliran Lateral1) Kondisi Petak di bagian Hulu/Atas Intersepsi Penutupan Tajuk : Kerapatan Tajuk Tebal dan susunan Lapisan Tajuk (strata) Lolos Tajuk Intensitas dan durasi Hujan Infiltrasi Laju Infiltrasi : Porositas (makro) Profil Tanah Intensitas Hujan dan Simpanan Permukaan Perkolasi Permeabilitas Tanah, Ketebalan Solum Evapotranspirasi2) Ketersediaan air tanah, cuaca dan kondisi tanaman Limpasan Permukaan Resultante semua komponen Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

42 Estimasi Neraca Air dalam Petak Tanaman saat terjadi hujan
DISKUSI Estimasi Neraca Air dalam Petak Tanaman saat terjadi hujan Diskusikan : Berapa proporsi masing-masing komponen ketika terjadi hujan 100 % Berapa besarnya limpasan permukaan dari berbagai macam penggunaan lahan ini Komponen apa saja yang berbeda? Mengapa demikian ? Komponen Siklus Air Hutan Alam Hutan Tnm Pinus Kebun Apel Sayuran : Kentang Presipitasi 100 Aliran Lateral Intersepsi Lolos Tajuk Infiltrasi Perkolasi Evapotrasnpirasi Limpasan Permukaan Komponen Siklus Air Hutan Alam Hutan Tnm Pinus Kebun Apel Sayuran : Kentang Presipitasi 100 Aliran Lateral ? Intersepsi Lolos Tajuk Infiltrasi Perkolasi Evapotrasnpirasi Limpasan Permukaan 1) Aliran lateral tergantung dari limpasan yang berasal dari petak dibagian hulu/atasnya 2) Evapotranspirasi sangat kecil (nol) karena durasi kejadian yang singkat dan cuaca hujan (kelembaban udara maksimum/jenuh) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

43 Contoh Neraca Air dari Kawasan Hutan/Pertanian
Hujan (Presipitasi) Limpasan Permukaan Infiltrasi Evapo(transpi)rasi 100% 40% 50% 10% Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

44 Apa saja yang bisa terbawa keluar dari Plot bersama dengan aliran permukaan ?
Material Tanah (sedimen) Bahan Organik : Pupuk Kandang (manure) Kompos Sampah, seresah Unsur-unsur kimia : Unsur Hara Pupuk Pestisida, Herbisida, dsb Lainnya ? Kondisi seperti apa yang bisa mendorong terangkutnya bahan2 tsb bersama limpasan permukaan ? Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

45 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi
Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

46 PETAK dan LANSEKAP Apakah hal-hal yang terjadi dalam petak akan sama dengan yang terjadi di lansekap ? Debit sungai merupakan akumulasi limpasan permukaan dari semua petak pertanian dan non pertanian dalam lansekap Jumlah sedimen yang terangkut sungai merupakan akumulasi dari erosi dari seluruh petak dalam lansekap Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

47 Apakah hal-hal yang terjadi di tingkat petak akan sama dengan di tingkat Lansekap ?
Indikator Kemungkinan 1 Kemungkinan 2 Limpasan Permukaan dan Debit Debit Banjir di sungai lebih besar dari jumlah semua limpasan yang keluar dari setiap petak dalam DAS Debit Banjir di sungai lebih kecil dari jumlah semua limpasan yang keluar dari setiap plot (petak) dalam DAS Erosi dan Sedimen Jumlah Sedimen yang terangkut di sungai lebih besar dari jumlah erosi (kehilangan tanah) dari setiap petak dalam DAS Jumlah sedimen yang terangkut di sungai lebih kecil dari jumlah erosi (kehilangan tanah) dari setiap petak dalam DAS Fungsi Lansekap (DAS) DAS atau lansekap tidak memiliki fungsi menahan (buffer) dan menyaring (filter). DAS atau lansekap mempunyai fungsi menahan (buffer) dan menyaring (filter). Pertimbangkan Longsor tebing sungai dan jalan Limpasan dari jalan dan pemukiman Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

48 Adanya cekungan alami (embung) dan relief mikro menjadi tempat singgah air permukaan sehingga tidak langsung mengalir ke sungai, meningkatkan kapasitas infiltrasi kawasan dan mengendapkan bahan terangkut air (sedimen dsb) Adanya strip filter atau buffer sepanjang bantaran/sempadan sungai bisa mengurangi jumlah sedimen yang bisa masuk ke sungai, sehingga air sungai bisa tetap jernih Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

49 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi
Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

50 Dimodifikasi dari sumber : Susswein, van Noordwijk and Verbist (2002)
Debit Banjir (tahunan) Jumlah Sedimen Terangkut Debit dasar (tahunan) Dimodifikasi dari sumber : Susswein, van Noordwijk and Verbist (2002) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

51 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi
Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

52 A Review on Organic Farming for Sustainable Agriculture
Ananata Ghimire . June, 2002 Organic farming seems to be more appropriate as it considered the important aspects like sustainable. Agriculture is the most important sector for ensuring food security, alleviating poverty and conserving the vital natural resources that the world’s present and future generation will be entirely dependent upon for their survival and well being, in the name of development, the environmental resources have been beyond comprehension. Acid rain, deforestation, depletion, smog due to automobiles and discharge of industrial pollution, soil degradation, depletion of ozone layer and discharge of toxic wastage by industrial units into rivers and oceans are some environmental problematic issues. Intensive use of inorganic fertilizers and pesticides has been an important tool in the drive for increased crop production. In fact more fertilizers consumption is a good indication of agricultural productivity but depletion of soil fertility is commonly observed in soils. Due to heavy use of chemical herbicides, pesticides and intensification of agricultural production during the past few decades has led to other harmful effects like nitrate in the ground water, contamination of fooding materials, eutrophication, stratospheric changes etc. High agricultural inputs are unlikely to be sustainable for very long unless the inputs are correctly judged in terms of both their quality and quantity. To escape from these harmful effects, the concept of organic farming was emerged from the conference of Atlanta in 1981. Organic Farming seems to be more appropriate as it considered the important aspects like sustainable natural resources and environment. It is a production system, which favors maximum use of organic materials like crop residues, FYM, compost, green manure, oil cakes, bio-fertilizers, bio-gas slurry etc. to improve soil health from the different experiment, microbial fertilizers like Rhizomic, Azotobacter, Blue green algae, Azolla etc. have increased the yield and also played important role for minimizing the harmful effect of pesticides and herbicides. Organic farming is a practical proposition for sustainable agriculture if adequate attention is paid to this issue. There is urgent need to involve more and more scientist to identify the thrust area of research for the development of eco-friendly production technology. Sumber: Department of Agriculture Extension and Rural Sociology Institute of Agriculture and Animal Science Rampur, Chitwan, Nepal

53 Prinsip Pengelolaan di Tingkat Plot :
PERBAIKAN NERACA AIR MENGURANGI LIMPASAN PERMUKAAN MENINGKATKAN INTERSEPSI MENINGKATKAN KAPASITAS INFILTRASI MENINGKATKAN KAPASITAS TANAH MENAHAN AIR MENINGKATKAN KAPASITAS PERKOLASI 1 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

54 Prinsip Pengelolaan di Tingkat Plot :
MENEKAN EROSI DAN PENCEMARAN AGROKIMIA MENGURANGI LIMPASAN PERMUKAAN MENEKAN LAJU LIMPASAN PERMUKAAN MELINDUNGI PERMUKAAN TANAH MENGURANGI PENGGUNAAN BAHAN AGROKIMIA 2 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

55 BMPs : (Tanaman) Penutup Tanah diantara Barisan Tanaman Pokok
Mulsa seresah tanaman di antara barisan tanaman jagung Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

56 Teknik Pengelolaan di tingkat lansekap :
PERBAIKAN NERACA AIR KAWASAN Meningkatkan LUAS lahan dengan tutupan permanen dan berlapis Meningkatkan kapasitas simpanan permukaan (surface storage) melalui kekasaran permukaan Meningkatkan kapasitas tanah untuk menahan air Meningkatkan kapasitas infiltrasi dan drainasi untuk pengisian groundwater Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

57 Teknik Pengelolaan di tingkat lansekap :
MENGURANGI EROSI DAN PENCEMARAN Mengendalikan laju aliran permukaan dengan cara mekanik dan biologi Meningkatkan luas kawasan dengan tutupan permanen Mengurangi dan mengendalikan penggunaan bahan agrokimia Membangun zona penyaring (filter) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

58 BAGAIMANA MERANCANG FILTER ATAU BUFFER ?
Sumber : Bruno Verbist (2009) Penanaman yang rapat di sepanjang KAKISU (Sempadan Sungai) Lembah Aliran Sungai Hutan Lindung Hutan Tanaman Pengendali Limpasan Kawasan Budidaya BAGAIMANA MERANCANG FILTER ATAU BUFFER ? Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

59 Manajemen pertanian terkait dengan kualitas air :
Praktek pertanian yang meningkatkan bahan organik dan biologi tanah Praktek konservasi tanah dan air untuk mengendalikan limpasan dan erosi Kombinasikan tanaman tahunan, semak, rumput dan tanaman semusim Tanaman yang bisa menangkap unsur hara seperti penutup tanah Kawasan penyangga antara lahan dengan tubuh air (sungai, danau, dsb) Pengelolaan irigasi untuk menghindari pencucian hara Mengintegrasikan ternak dalam sistem pertanian Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

60 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi
Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

61 PEMBANGUNAN BERKELANJUTAN
…. Proses yg secara berkelanjutan mengoptimalkan manfaat SDL melalui penyerasian aktivitas ekonomi sesuai dg kapabilitas dan daya dukungnya Peningkatan Kesejahteraan MASYARAKAT Soemarno, 2005 PRODUKSI-DISTRIBUSI-KONSUMSI Konservasi Rehabilitasi Penghematan

62 INDIKATOR LINGKUNGAN PERTANIAN SEHAT
Tidak ada tanah yang terbuka (bero) Dalam selokan dan parit mengalir air yang jernih Terdapat hewan/binatang liar sangat banyak Dijumpai ikan pada selokan dan sungai yang mengalir melalui lahan pertanian Pada Lansekap Pertanian dijumpai aneka vegetasi (sangat beragam) Preston Sullivan, 2003 Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

63 ISU-ISU STRATEGIS Keterbatasan income rumah-tangga
Kualitas hidup manusia di daerah miskin / kritis semakin menurun , indikatornya: Keterbatasan income rumah-tangga Penyakit akibat kesehatan lingkungan Pudarnya Budaya- Kearifan Masyarakat Gizi Anak BALITA Kualitas Kawasan Konservasi/ Lindung

64 Contoh Indikator Fungsi Hidrologi DAS
Karakteristik Lokal Fungsi DAS (kriteria) Relevansi bagi pengguna Indikator Curah hujan Bentuk lahan Jenis tanah Kedalaman akar (dari vegetasi alami) Transmisi air Pengguna air di daerah hilir Ketersediaan air sepanjang waktu Menyangga pada kejadian puncak hujan Masyarakat yang tinggal di bantaran sungai dan bantaran banjir Tinggi muka air sampai batas terkendali Infiltrasi & melepaskan air secara bertahap Masyarakat yang tidak memiliki sistem penyimpanan air Sumur dangkal yang tidak kering Memelihara kualitas air Masyarakat yang tidak memiliki sistem purifikasi, PLTA Ketersediaan air bersih sepanjang waktu Karakteristik Lokal Fungsi DAS (kriteria) Relevansi bagi pengguna Indikator Curah hujan Bentuk lahan Jenis tanah Kedalaman akar (dari vegetasi alami) Transmisi air Pengguna air di daerah hilir Ketersediaan air sepanjang waktu Menyangga pada kejadian puncak hujan Masyarakat yang tinggal di bantaran sungai dan bantaran banjir Tinggi muka air sampai batas terkendali Infiltrasi & melepaskan air secara bertahap Masyarakat yang tidak memiliki sistem penyimpanan air Sumur dangkal yang tidak kering Memelihara kualitas air Masyarakat yang tidak memiliki sistem purifikasi, PLTA Ketersediaan air bersih sepanjang waktu Mengurangi longsor Masyarakat yang tinggal di kaki bukit Intensitas kejadian longsor Mengurangi erosi Petani, Nelayan, PLTA Ketebalan seresah & top- soil, biodiversitas ikan bioindikator bentos Mempertahankan iklim mikro Petani & wisatawan Suhu dan kelembaban Karakteristik Lokal Fungsi DAS (kriteria) Relevansi bagi pengguna Indikator Curah hujan Bentuk lahan Jenis tanah Kedalaman akar (dari vegetasi alami) Transmisi air Pengguna air di daerah hilir Ketersediaan air sepanjang waktu Karakteristik Lokal Fungsi DAS (kriteria) Relevansi bagi pengguna Indikator Curah hujan Bentuk lahan Jenis tanah Kedalaman akar (dari vegetasi alami) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012 (Sumber : Farida & Van Noordwijk, 2006)

65 Contoh Indikator Fungsi Hidrologi DAS Kali Konto
Perubahan distribusi musiman aliran sungai di (A) DAS Kalikonto (Indonesia), dimana pada periode ke II ( ) terjadi alih guna hutan menjadi lahan pertanian dalam skala besar (sumber: Bruijnzeel, 1990) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

66 Pencemaran dari Lahan Pertanian
Potensi Pencemar Air dari Lahan Pertanian : Nitrogen Pospor Logam Berat Kotoran Ternak (manure) Pestisida Patogen (penyebab penyakit pada Manusia) Sedimen Pemberian Bahan Agrokimia (Pupuk dan Pestisida) dan Bahan Organik (Pupuk Kandang) yang berlebihan berpotensi menjadi potensi sumber pencemar Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

67 Kehilangan Air Bersih Kehilangan Biodiversitas Kehilangan Cadangan Karbon Penebangan Hutan dan Alih Fungsi Hutan ke Pertanian Pertanian dengan Upaya Konservasi Mandiri Pertanian dengan Upaya Konservasi Imbalan Jasa Keuntungan yang diperoleh Pemilik Lahan (PETANI) Tambahan biaya yang ditanggung masyarakat (Kerugian MASYARAKAT) Diolah & dikembangkan dari : Pagiola (2003) Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

68 Layanan Lingkungan : Mereka perlu air bersih
Water quality? Foto2 : Kurniatun Hairiah Sumber: Pertanian Berlanjut: Lansekap Pertanian dan Hidrologi. Widianto 2012

69 Water percolates to deeper layers and infiltrates from the pools.
Need for drainage During heavy rainfall the upper soil layers become saturated and pools may form. Water percolates to deeper layers and infiltrates from the pools. Part of the water present in the saturated upper soil layers flows downward into deeper layers and is replaced by water infiltrating from the surface pools. When there is no more water left on the soil surface, the downward flow continues for a while and air re-enters in the pores of the soil. This soil is not saturated anymore. Diunduh dari Sumber: ….. 17/10/2012

70 GROUNDWATER TABLE …. After heavy rainfall the groundwater table may rise and reach the rootzone The water flowing from the saturated soil downward to deeper layers, feeds the groundwater reservoir. As a result, the groundwater level (often called groundwater table or simply water table) rises. Following heavy rainfall or continuous over-irrigation, the groundwater table may even reach and saturate part of the rootzone. Again, if this situation lasts too long, the plants may suffer. Measures to control the rise of the water table are thus necessary. The removal of excess water either from the ground surface or from the rootzone, is called drainage. Diunduh dari Sumber: ….. 17/10/2012

71 SOIL PROFILE…. A very general and simplified soil profile can be described as follows: The plough layer (20 to 30 cm thick): is rich in organic matter and contains many live roots. This layer is subject to land preparation (e.g. ploughing, harrowing etc.) and often has a dark colour (brown to black). The deep plough layer: contains much less organic matter and live roots. This layer is hardly affected by normal land preparation activities. The colour is lighter, often grey, and sometimes mottled with yellowish or reddish spots. The subsoil layer: hardly any organic matter or live roots are to be found. This layer is not very important for plant growth as only a few roots will reach it. The parent rock layer: consists of rock, from the degradation of which the soil was formed. This rock is sometimes called parent material. Diunduh dari Sumber: ….. 17/10/2012

72 THE GROUNDWATER TABLE ….
Part of the water applied to the soil surface drains below the rootzone and feeds deeper soil layers which are permanently saturated; the top of the saturated layer is called groundwater table or sometimes just water table. Diunduh dari Sumber: ….. 17/10/2012

73 It covers usually a limited area.
Perched groundwater table…. A perched groundwater layer can be found on top of an impermeable layer rather close to the surface (20 to 100 cm). It covers usually a limited area. The top of the perched water layer is called the perched groundwater table. The impermeable layer separates the perched groundwater layer from the more deeply located groundwater table Diunduh dari Sumber: ….. 17/10/2012

74 Depth of the groundwater table….
The depth of the groundwater table varies greatly from place to place, mainly due to changes in topography of the area. In one particular place or field, the depth of the groundwater table may vary in time. Following heavy rainfall or irrigation, the groundwater table rises. It may even reach and saturate the rootzone. If prolonged, this situation can be disastrous for crops which cannot resist "wet feet" for a long period. The groundwater table can also be very deep and distant from the rootzone, for example following a prolonged dry period. Diunduh dari Sumber: ….. 17/10/2012

75 Effective rainfall (8) = (1) - (4) - (5) - (7)
HUJAN EFEKTIF…. Effective Rainfall When rain water ((1) in Fig. 63) falls on the soil surface, some of it infiltrates into the soil (2), some stagnates on the surface (3), while some flows over the surface as runoff (4). When the rainfall stops, some of the water stagnating on the surface (3) evaporates to the atmosphere (5), while the rest slowly infiltrates into the soil (6). From all the water that infiltrates into the soil ((2) and (6)), some percolates below the rootzone (7), while the rest remains stored in the rootzone (8). Effective rainfall (8) = (1) - (4) - (5) - (7) Diunduh dari Sumber: ….. 17/10/2012

76 Effective rainfall and depth of the rootzone….
Soil water stored in deep layers can be used by the plants only when roots penetrate to that depth. The depth of root penetration is primarily dependent on the type of crop, but also on the type of soil. The thicker the rootzone, the more water available to the plant. Diunduh dari Sumber: ….. 17/10/2012

77 The effective rainfall is thus lower in sloping areas.
Effective rainfall and topography…. Topography On steep sloping areas, because of high runoff, the water has less time to infiltrate than in rather flat areas. The effective rainfall is thus lower in sloping areas. Diunduh dari Sumber: ….. 17/10/2012

78 Initial soil moisture content
Effective rainfall and initial soil moisture content…. Initial soil moisture content For a given soil, the infiltration rate is higher when the soil is dry than when it is moist. This means that for a rain shower occurring shortly after a previous shower or irrigation, the infiltration rate is lower and the surface runoff higher . . Effective rainfall and initial soil moisture content Diunduh dari Sumber: ….. 17/10/2012

79 Maximizing Irrigation Efficiency and Water Conservation
MAXIMIZE THE AMOUNT OF WATER ENTERING THE TURFGRASS ROOTZONE (STORAGE) BY: controlling water movement below the root zone (leaching), minimizing evaporative losses, controlling surface water runoff and ponding of irrigation water. Diunduh dari Sumber: 17/10/2012

80 Forest hydrological cycle (Hélie et al., 2005)….
Diunduh dari Sumber: 17/10/2012

81 How much water do forests use?….
Trees and forests have the ability to use more water than shorter types of vegetation. In general, conifers lose between 25 to 45% of annual rainfall by interception, compared to 10 to 25% for broadleaves and almost 0% for grass. Conifers tend to lose an additional 300 mm to 350 mm per year due to transpiration, compared to 300 mm to 390 mm for broadleaves and 400 mm to 600 mm for grass. Diunduh dari Sumber: 17/10/2012


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